[Qemu-devel] [PATCH RFC v4 00/13] Dirty bitmaps migration

[Vladimir Sementsov-Ogievskiy]

These patches provide dirty bitmap migration feature. Only named dirty
bitmaps are to be migrated. Migration may be enabled using migration
capabilities.

v4 significant changes:
 0001: tiny bugfix: out[i] -> out[i-start], same for 'in'
 0007: set chunk size to 1kb, disable live iteration for
       migrating data < 1mb size.

 tests: only one with md5 sum is here. used function event_wait
        by John Snow. (I hope, you don't mind me just adding this
        function with your 'Signed-off-by')

 rfc: This patch set is based on v13 of
      "block: incremental backup series" by John Snow, which are
      not pushed yet.

v3:
 based on v13 of "block: incremental backup series" by John Snow.

 changes from v2:
 removed patch for adding dirty parameter (migration capablities used
 instead).
 
 0001: printf's dropped, qapi used
 0002: part0 -> zeroes
 0003: part0 -> zeroes
 0005: dirty_dirty -> meta
       add comments about meta bitmap
       
 0006: the format is changed, nodes used instead of devices.

 other patches are new.

 rfc: there are two tests. They are the same but using different
 interfaces: md5 checksum of the bitmap last layer in query-block or
 separate query-block-dirty-bitmap with dirty bitmap regions.
 The second form is more appropriate for debugging, the first is more
 appropriate for simple regression control. Which should go to
 upstream?

v2:
 1. bug-fixes, that are already in upstream, and renaming of function
 bdrv_reset_dirty_bitmap (which is already in Snow's series) are
 dropped
 2. bitmap store/restore: the concept renamed to serialization, added
 function hbitmap_deserialize_part0, to not transfer zero blocks
 3. migration dirty parameter: added description comment
 4. Other patches are new.

v2.rfc:
Actually, in this version of the series I'm trying not use
migration/block.c at all. Instead a separate migration unit is added
in the new file migration/dirty-bitmap.c. Now bitmaps are migrated
like blocks in block migration, they have their "dirty-dirty" bitmaps,
for tracking set/unset changes during migration.

The advantages are:
  - no complications of migration/block.c
  - separate dirty-dirty bitmaps provide handling of "unset's"
  - more effective meta-data/data ratio - no tiny bitmap-blocks.



v1:
These patches provide dirty bitmap migration feature. Only named dirty
bitmaps are to be migrated. Migration is made as a part of block
migration in block-migration.c.

Dirty bitmap migration may be enabled by "dirty" parameter for qmp migrate
command. If "blk" and "inc" parameters are false when "dirty" is true
block migration is actually skipped: no allocatoions, no bdrv_read's,
no bdrv_write's, only bitmaps are migrated.

The patch set includes two my previous bug fixes, which are necessary
for it. The patch set is based on Incremental backup series by John
Snow.

*** BLURB HERE ***

Vladimir Sementsov-Ogievskiy (13):
  hbitmap: serialization
  block: BdrvDirtyBitmap serialization interface
  block: tiny refactoring: minimize hbitmap_(set/reset) usage
  block: add meta bitmaps
  block: add bdrv_next_dirty_bitmap()
  qapi: add dirty-bitmaps migration capability
  migration: add migration/block-dirty-bitmap.c
  iotests: maintain several vms in test
  iotests: add add_incoming_migration to VM class
  iotests: add event_wait to VM class
  qapi: add md5 checksum of last dirty bitmap level to query-block
  iotests: add dirty bitmap migration test
  migration/qemu-file: make functions qemu_(get/put)_string public

 block.c                        |  98 +++++-
 include/block/block.h          |  22 ++
 include/migration/block.h      |   1 +
 include/migration/migration.h  |   1 +
 include/migration/qemu-file.h  |  17 +
 include/qemu/hbitmap.h         |  67 ++++
 migration/Makefile.objs        |   2 +-
 migration/block-dirty-bitmap.c | 693 +++++++++++++++++++++++++++++++++++++++++
 migration/migration.c          |   9 +
 migration/qemu-file.c          |  18 ++
 qapi-schema.json               |   5 +-
 qapi/block-core.json           |   4 +-
 tests/qemu-iotests/117         |  84 +++++
 tests/qemu-iotests/117.out     |   5 +
 tests/qemu-iotests/group       |   1 +
 tests/qemu-iotests/iotests.py  |  19 +-
 util/hbitmap.c                 | 106 +++++++
 vl.c                           |   1 +
 18 files changed, 1144 insertions(+), 9 deletions(-)
 create mode 100644 migration/block-dirty-bitmap.c
 create mode 100755 tests/qemu-iotests/117
 create mode 100644 tests/qemu-iotests/117.out

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1.9.1